| 摘要 |
A control loop ( 10 ) for producing an output signal with a stable nominal frequency is provided. The control loop includes inputs for reference ( 11 ) and oscillator ( 25 ) output signals, a beat frequency generator ( 12 ) for producing a signal with a frequency that is the difference between the oscillator and reference signal frequencies, an ADC ( 14 ) to convert the beat frequency to a digital beat frequency signal, an estimator ( 17 ) for estimating the frequency or phase of the beat signal, an adder ( 18 ) for combining an offset and modulation signal and the estimated frequency or phase of the beat signal into an added signal, and a DAC ( 23 ) for generating an analogue control signal for controlling the oscillator output frequency. |
